Hollow propeller



. Jan. 15,1935. w, s, HOOVER HOLLOW PROPELLER Filed Oct. 27, 1931 INVENTOR.

A TTORNE Y.

Patented Jan. 15, 1935 t r g STATES Walter S. Hoover, 'liii'aril, Pa, assignor of onehall to Patrick H Crow, Meade, Pa.

Application em er 27, rear, Serial No. 571,343

' Claims. mi. 170-159) This invention relates to improvements in probeing provided with a strut 3, the extended edge peller blade structures more particularly to pro- 4 of which is of the same contour as the face of pellers of hollow steel or duraluminum and it is the propeller blade with which it cooperates when among the objects thereof to provide a composite set to its proper position. I

5 blade structure having a reinforcing strut ex- The strut member is provided with slots 5 and a 6 tending transversely of the blade and in which the other edge of the blade section is provided the parts shall be firmly interlocked and secured with notches 6 in alineinent with the slots 5 of in a manner to render the blade unbreakable at the strut. The hub portion of the blade section the joint. is provided with grooves 7 to interlock with the 10 A further object of the invention is the prohub casting (not shown) in which the propeller 0 vision of a novel propeller design consisting of blades are mounted. two sections one of which is provided with a rein- The half section 1 shown in Figures 1 and 4 of forcing strut, and the other with fingers adapted the drawing, is provided with fingers 8 of varying to interlock with slots provided in the cooperating lengths corresponding to :the thickness of the section, and which shall be adapted to have the blade section, namely, the dimension from the 15 reinforcing struts, the fingers, 'slots,'and the camedge of the notches 6 to the slots 5. v ber formed by drop forge or die stamping meth- The section 1 constitutes the top or leading edge ods either simultaneously or by a succession of of the propeller and the section 2 the trailing edge, operations. the section 1 having a camber 9 on its face as A further object of the invention is the provishown in Figure 1. 0

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sion of hollow propeller structures in which the The half sections of Figures 1, 2, 4 and 5 are blade sections are divided into a plurality ofcomformed by either drop forge or die stamping oppartments which may be utilized as exhaust paserations, the strut and the camber 9 all being sages communicating with scavaging slots at the formed-simultaneously and the interlocking fintrialing edge of the propeller blades, or 'as air ingers 8 and the half section 2 may be provided with take passages communicating with air scoops prothe-slots 5 and notches 6 in the die stamping vided on the leading edge of the blade, the object operation. I of the air scoops being to eliminate the use of a The half sections 1 and 2 are assembled in the supercharger for aeroplane engines. manner shown in Figure 5 of the drawing where- These and other objects of the invention will in the fingers 8 of the section 1 are shown dis- 30 become more apparent from a consideration of posed through the slots 5 of the section 2 and the the accompanying drawing constituting a part 'strut 3 is shown with its outer face in abutment hereof in which like reference characters desigwith the edges of the section 1.

nate like parts and in which: By bending the sections in the direction shown Figure 1 is a bottom plan view of the top sec.- by the arrow, the fingers 8 of section 1 will lie 86 tion of the propeller; v I in the notches 6 of the edge of section 2 and per- Figure 2 a top plan view of the bottom or trailmit the closing of the half sections with the fingers ing section of the propeller; I 8 projecting through the slot 6 with the extreme Figure 3 a vertical section extending through ends of the fingers contiguous with the face of 40 the leading and trailing edges of the propeller the propeller blade, and so assembled the strut 3 40 blade; extends transversely of the hollow blade section Figure 4 a rear elevation of the assembled blade and divides the blade into chambers 10 and 11. illustrating the air scoop and scavaging slot re- After the strut and fingers of the propeller secspectilvely located adjacent the. hub and tip of tions have been bent to their assembled position, the b ade; Figure 5 an end elevation viewed from the hub section is welded at 12 substantially 90 from the end illustrating the manner of interlocking the leading and trailing edges thus assuring a stronghalf section; and rigid joint at the mid section of the blade Figure 6 an end elevation -,of .the assembled which is the point of least stress so that very lit- 50 blade structure as viewed from the hub end theretle strain is acting on the Joint.

of. Both edges of the blade are welded along the C with reference to the several figures of the root section, namely, the hub portion to produce drawing, the structure therein illustrated coma strong construction.

prises the two half sections generally designated In the welding of the joint the usual chamfer the open seam along the notched edge 6 of the u by the reference characters 1 and 2, the section'2 13 may be provided as shown in Figure 8 of the 66 1 running the full length of the blade and parallel to the propulsive stresses, produces greater rigidity throughout the length of the blade.

The construction producing the above enumerated characteristics, is particularly desirable for variable pitch propellers in which the bending moments on the blades are much greater than in rigid propeller construction, also by means of the reinforcing transverse strut and the interlocking fingers, a light weight metal such as duraluminum may be utilized with safety, and steel propellers may be made to resist or stand up under increased horse power at high peripheral speeds which is the trend in' modern aeroplane propulsion design. A minimum weight propeller con structed of duraluminum, also relieves the centrifugal thrust load on the propeller and is therefore greatly desired if it can be constructed with sufiicient rigidity and strength.

By providing scavag'ing slots 14 on the trailing edge of the propeller adjacent the tip, fluttering of the blade is prevented and ice formation is reduced or eliminated.

By providing an air scoop 15 Figures 3 and 4 on the leading edge of the blade adjacent the hub end or blade root, air can be drawn into the propeller and conducted through the hub structure to the engine to take the place of a supercharger now commonly employed in aeroplanes designed for high altitude pflying. Similarly, the exhaust of the engine may be conducted through the hub into the chamber 11 from which it passes through the scavaging slots 14 near the tip of the propeller. I

By means of the strut 3 partitioning the blade into two chambers, both the scoops and scavaging slots may be utilized in the same propeller blade so long as provision is made for conducting the air and exhaust through the hub to separate conduits.

Although one embodiment of the invention has been herein illustrated and described, it will be evident to those skilled in the art that various modifications may be made in the details of co nstruction without departing from the principles herein set forth.

I claim:

l. A propeller blade structure comprising a pludrawing in which the fused metal is' deposited in rallty of longitudinal sections joined by interlocking said sections on one side substantially 90* from the leading and trailingedges of the blade and welding the other edge of the sections along their abutting faces substantially 180 from the interlocked Joint.

2. A propeller blade structure comprising two 1 longitudinal half sections formed to a leading 'and trailing section of predetermined shape and contour, one of said sections having fingers projecting thereon and the other of said sections having slots and notches, said sections being interlocked by disposing the fingers of one section through the slots and notches in said other section, and welding the joined sections along the open seam.

3. A'prop eller blade structure comprising a pair of half sections, one of which constitutes the leading edge of the propeller and the other of which constitutes thetrailing edge, one of said sections being provided with fingers and the other with a strut of a width corresponding to the thickness of the hollowness of the blade, said strut having slots and the other edge of said strut section having notches, said fingers slots and notches being equally spaced and adapted to cooperate to form an interlock of the two propeller sections, said interlock sections being welded along their joined faces substantially at right angles to the leading and trailing edges of the blade.

4. A propeller blade structure comprising a pair of half sections one of which is provided with fingers adapted to extend the full width of the section, and the other of which is provided with interlocking slots and notches spaced to receive said of the blade whereby the blade is divided into separate compartments one of said compartments being provided with slots at the trailing edge of the blade tip for routing fumes from the hub section and the other of said compartments having a scoop at the leading edge adjacent the hub end of the blade.

' WALTER S. HOOVER. 

